Hey everyone, I was wondering how one can figure out the effective range of a lens. For example for canon's 17-85 mm, I was told that it has an equivalent range of 27-136 mm- how do you get that and why is that so? I was also wondering how the value in mm equates to actual distance that lens can shoot in either feet, yards w/e. The more I think about it, the more it seems like picking a lens for a particular photo is like picking the right club for a golf shot!!